That's why Lieberman says he and other Congressmen introduced a bill to require minimum security levels at the most critical private cyber networks, which are prime targets.

After the bill was blocked, at the urging of the U.S. Chamber of Commerce, its sponsors dropped the minimum-security requirement and opted for liability protections to companies that voluntarily adopt the security standards.

But the Chamber of Commerce still opposed the bill, saying better information sharing between private companies and the government will solve the problem.

"But information sharing alone is a half-step, helping only some networks some of the time," Lieberman argues, saying it won't help if networks remain vulnerable.

"Many critical systems don’t even have the personnel or technological capabilities to use shared information or to gather information to share with others."

Ironically, the Chamber itself was victimized by a "sustained, widespread hack" by the Chinese and didn't realize it until informed by the FBI, Lieberman says.

Deputy Defense Secretary Ashton Carter, Lieberman notes, has warned that: "There is a market failure at work here. ... Companies just aren’t willing to admit vulnerability to themselves, or publicly to shareholders."

Former security chiefs have warned that the United States must be prepared for "cyber 9/11." And it's a question of when that attack will happen, not if.

"We must act before another catastrophe occurs," he writes.

President Barack Obama has said he would use his executive powers to strengthen cyber defenses, but he cannot offer liability protections or require businesses to report major cyber breaches without Congressional actions, Lieberman says.

In an op-ed piece for The Wall Street Journal this summer, Obama said foreign governments, criminal syndicates and lone hackers are probing critical networks for vulnerabilities every day. Computer systems in critical sectors, such as nuclear and chemical industries, are being increasingly targeted, Obama says, urging Congress to pass a cyber security bill.